Chemistry Flashcards
(23 cards)
What is the atomic number?
The number of protons in an atom.
What is the mass number?
The total number of protons and neutrons.
How do you calculate the number of neutrons?
Neutrons = Mass number - Atomic number.
What is an isotope?
Atoms of the same element with the same number of protons but different numbers of neutrons.
How do you calculate relative atomic mass (Ar)?
Multiply each isotope’s mass number by its % abundance, add the results, and divide by 100.
What is an ion?
A charged particle formed when an atom gains or loses electrons.
How do metal atoms form ions?
By losing electrons to form positive ions (cations).
How do non-metals form ions?
By gaining electrons to form negative ions (anions).
What is ionic bonding?
The strong electrostatic attraction between oppositely charged ions.
Why do ionic compounds conduct electricity when molten or dissolved?
Because the ions are free to move and carry charge.
Why don’t solid ionic compounds conduct electricity?
The ions are fixed in place in a lattice and cannot move.
What are the Group 1 metals called?
Alkali metals.
What happens when Group 1 metals react with water?
They form a hydroxide and hydrogen gas.
Why is potassium more reactive than sodium?
It has more electron shells, so the outer electron is more easily lost.
What is observed when sodium reacts with water?
Effervescence, floating and moving metal, and it melts into a ball.
What is the general equation for Group 1 metals reacting with water?
Metal + Water → Metal hydroxide + Hydrogen.
What is a displacement reaction?
A more reactive metal displaces a less reactive metal from its compound.
What happens when magnesium is added to copper(II) sulfate?
Magnesium displaces copper: copper forms as a solid, solution turns colourless.
What is the order of reactivity based on reactions with acid and water?
More reactive metals react faster/more violently.
How do you make a soluble salt from an insoluble base?
Add excess base to acid → filter → heat filtrate → crystallise.
Why do you add base in excess?
To ensure all acid reacts and the salt formed is pure.
Why do you filter the mixture after reacting acid and base?
To remove unreacted excess base.
How do you get crystals from a solution?
Heat to evaporate some water, then cool slowly for crystals to form.
